This project addresses biological neural networks (NNs) in the auditory system in the context of high-channel count electrodes. We propose to extend our past work on recording in the cochlear nuclei (CN) and inferior colliculus (IC) using thin-film electrode technology to address technical, biological, and theoretical questions about data collection and analysis and neural circuit identification. Both acute and chronic multiunit recording at CN, IC, and auditory cortex (AC) of guinea pig will be used to address these questions. The general aims of this project are to apply the enhanced data gathering made possible by the thin-film, multicontact electrode technologies which concern this Resource Center to advance network estimation for NNs in general, and to obtain a better understanding of neural processing in the networks of the auditory system. The areas of work include 1) the study of waveforms recorded with multicontact electrodes including field potentials and the detection of discharges and their parsing into valid spike trains; 2) the collection and analysis of multiple spike train data from CN, IC, and AC using sound stimuli and local chemical and electrical stimuli in acute and chronic guinea pig preparations; 3) the study of NN identification problems using simulations of classes of networks and experimental data from thin-film electrodes.